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📛 NAME

EVP_MAC-CMAC - The CMAC EVP_MAC implementation

🚀 Quick Reference

Use Case	Command	Description
🔑 Create CMAC context	EVP_MAC_fetch(NULL, "CMAC", "provider=default")	Fetch the CMAC implementation for use
🔐 Set underlying cipher	EVP_MAC_CTX_set_params(ctx, { "cipher": "AES-128-CBC" })	Specify the block cipher (e.g., AES)
🔑 Set MAC key	EVP_MAC_init(ctx, key, keylen)	Initialize with the secret key
📏 Get MAC size	EVP_MAC_CTX_get_mac_size(ctx)	Retrieve the output MAC length
📦 Compute final MAC	EVP_MAC_final(ctx, mac, &maclen)	Obtain the CMAC tag

📝 DESCRIPTION

Support for computing CMAC MACs through the EVP_MAC API.

This implementation uses EVP_CIPHER functions to get access to the underlying cipher.

🔍 Identity

This implementation is identified with this name and properties, to be used with EVP_MAC_fetch():

• "CMAC", "provider=default" or "provider=fips"

⚙️ Supported parameters

The general description of these parameters can be found in "PARAMETERS" in EVP_MAC(3).

Set parameters (via EVP_MAC_CTX_set_params()):

• 🔑 "key" (OSSL_MAC_PARAM_KEY) <octet string> — Sets the MAC key. Setting this parameter is identical to passing a key to EVP_MAC_init(3).
• 🔐 "cipher" (OSSL_MAC_PARAM_CIPHER) <UTF8 string> — Sets the name of the underlying cipher to be used.
• 🏷️ "properties" (OSSL_MAC_PARAM_PROPERTIES) <UTF8 string> — Sets the properties to be queried when trying to fetch the underlying cipher. This must be given together with the cipher naming parameter to be considered valid.

Get parameters (via EVP_MAC_CTX_get_params()):

• 📏 "size" (OSSL_MAC_PARAM_SIZE) <unsigned integer> — The "size" parameter can also be retrieved with EVP_MAC_CTX_get_mac_size(). The length of the "size" parameter is equal to that of an unsigned int.
• 📦 "block-size" (OSSL_MAC_PARAM_SIZE) <unsigned integer> — Gets the MAC block size. The "block-size" parameter can also be retrieved with EVP_MAC_CTX_get_block_size().

👀 SEE ALSO

EVP_MAC_CTX_get_params(3), EVP_MAC_CTX_set_params(3), "PARAMETERS" in EVP_MAC(3), OSSL_PARAM(3)

©️ COPYRIGHT

Copyright 2018-2021 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at https://www.openssl.org/source/license.html.

📛 NAME 🚀 Quick Reference 📝 DESCRIPTION 👀 SEE ALSO ©️ COPYRIGHT